1. Field of the Invention
This invention relates to a recording and reproducing apparatus, such as a still video camera (hereinafter referred to as an SV camera) or the like and more particularly to an apparatus which is capable of performing not only recording but also reproduction by means of a reproducing circuit which is arranged either within or not within the camera.
2. Description of the Related Art
The conventional SV camera uses, for example, a magnetic sheet or the like. Generally, for reduction in size, weight and cost, the SV camera has been arranged to have a recording function but no reproducing function. Hence, a discrete reproducer must be used for visual reproduction of a recorded image.
Of late, there has arisen a tendency to provide the SV camera either with an adapter or an internal reproducing function to permit visual reproduction for confirmation or observation of the image recorded by the camera.
The SV camera of the kind performing a reproducing operation with an adapter is, however, arranged in general to perform recording by sequentially shifting a magnetic head either from the outer periphery or from the inner periphery of the recording medium while detecting recorded tracks of the medium and by bringing it to a stop at an unrecorded track in a sequential manner. However, this sequence of the recording operation is not applicable as it is to a reproducing operation. Therefore, the reproducing operation has been complex and it has been difficult to readily obtain a recorded picture as desired.
The conventional magnetic recording and reproducing apparatus has been provided with a switching device which serves combined functions as recording means and as reproducing means and uses a magnetic head both for recording and for reproduction. In the conventional magnetic recording and reproducing apparatus, the magnetic head must be switched from a recording mode over to a reproducing mode and vice versa through such an arrangement as shown in FIG. 1 of the accompanying drawings. In FIG. 1, the illustration includes a recording amplifier 1; the magnetic head 2, a reproduction amplifier 3 and a switch SW. The switch SW of FIG. 1 which represents the above stated switching device has been composed of a relay in most cases. However, a switching element such as a transistor has recently come to replace the relay in many cases for the purpose of allowing reduction in size and weight, obtaining quick responsivity and saving electric energy, etc.
FIG. 2 shows a circuit arrangement of the conventional electronic switching circuit and FIG. 3 the wave forms of the outputs of various parts of FIG. 2. The arrangement of FIG. 2 includes capacitors Cl and C2; transistors Tr1 and Tr2; and resistors R1, R2 and R4 while parts which are the same as or equivalent to those of FIG. 1 arc indicated by the same reference numerals. The illustration in FIG. 2 includes input terminals a and b arranged to receive pulses for change-over between recording and reproduction. The polarity of the incoming pulses is as shown at parts a and b of FIG. 3. Parts c and d of FIG. 3 show the wave forms of the various parts which obtained upon receipt of these incoming pulses.
Referring to FIG. 2, when the switching circuit is shifted from a reproducing mode to a recording mode, the potential at a point c rises from zero volt up to a bias voltage VB produced from the recording amplifier. Meanwhile, the potential at another point d remains at zero.
When the recording mode is switched over to the reproducing mode, the potential at the point c is grounded and changes from the voltage VB to zero volt with the transistor Tr1 turned on. Meanwhile, the point e is opened with the transistor Tr2 turned off. As a result, the potential at the point d temporarily drops down to a minus value of the voltage vB and then rises according to a time constant defined by the capacitor Cl and the resistor R4. In such a way, a large negative voltage is applied to the point d, so that the above stated current flows via the head 2.
However, when the conventional apparatus is switched from the recording mode over to the reproduction mode, the transient current flowing through the magnetic head leaves some fixed flaw in a reproduced picture. This has been a problem with the conventional apparatus.